Patentleft (also patent left, copyleft-style patent license or open patent) is the practice of licensing patents (especially biological patents) for royalty-free use, on the condition that adopters license related improvements they develop under the same terms. Copyleft-style licensors seek "continuous growth of a universally accessible technology commons" from which they, and others, will benefit.[1][2]

Patentleft is analogous to copyleft, a license which allows distribution of a copyrighted work and derived works, but only under the same terms.

Uses

The Biological Innovation for Open Society (BiOS) project implemented a patentleft system to encourage re-contribution and collaborative innovation of their technology. BiOS holds a patented technology for transferring genes in plants, and licenses the technology under the terms that, if a license holder improves the gene transfer tool and patents the improvement, then their improvement must be made available to all the other license holders.[3]

The open patent idea is designed to be practiced by consortia of research-oriented companies[4] and increasingly by standards bodies. These also commonly use open trademark methods to ensure some compliance with a suite of compatibility tests, e.g. Java, X/Open both of which forbid use of the mark by the non-compliant.

On October 12, 2001 the Free Software Foundation and Finite State Machine Labs Inc. (FSMLabs) announced a GPL - compliant open-patent license for FSMLabs' software patent, US 5995745. Titled the Open RTLinux patent license Version 2, it provides for usage of this patent in accordance with the GPL.[5]

Example

Person A has a patent, and licenses it under a patentleft license.

Person B has two patents in her product and wants to use Person A's patents in that product. Person B also wants to charge royalties for her two patents. She decides to use Person A's patent, but now must license her patents, royalty-free, under the same terms as Person A's patent.

Person C has three patents in his product and wants to use Person B's two patents in that product, but doesn't want to use Person A's patent. Person C also wants to charge royalties for his three patents. He decides to use Person B's patent, but now must license his patents, royalty-free, under the same terms as Person A's patent.